Washing machine

ABSTRACT

A washing machine including a suspension to support an outer tub so as to absorb vibrations of the outer tub. The suspension includes an outer tub supporter disposed so as to be movable along a support rod, an elastic member to elastically support the outer tub supporter, a first friction unit to apply frictional force between the first friction unit and the support rod, and a second friction unit disposed above the first friction unit and movable along the support rod, the second friction unit applying frictional force between the second friction unit and the support rod, the second friction unit being displaceable relative to the outer tub supporter within a space delimited by the outer tub supporter.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Korean Patent Application No. 10-2014-0087717, filed on Jul. 11, 2014 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

The present disclosure relates to a washing machine, and more particularly, to a washing machine which is capable of effectively attenuating vibrations.

2. Description of the Related Art

Generally, a washing machine is an apparatus that washes laundry using, for example, emulsified detergent, water streams generated by the rotation of a wash tub or a pulsator, and shock applied by the pulsator. The washing machine implements washing, rinsing, and/or dehydration to remove contaminants attached to laundry (hereinafter referred to as “clothing”) using the action of detergent and water.

A conventional washing machine includes a casing forming the external appearance of the washing machine, an outer tub suspended inside the casing, and an inner tub rotatably provided inside the outer tub. In addition, the washing machine further includes a suspension to prevent the outer tub from vibrating due to the rotation of the inner tub and/or the pulsator.

The suspension is typically configured to attenuate vibrations generated from the outer tub using, for example, the elasticity/restoration of springs or the viscosity of fluid. However, although this suspension may effectively attenuate vibrations in the normal vibration state, in which the outer tub vibrates within a given amplitude range, it is limited in the attenuation of vibrations in the excessive vibration state, in which the outer tub vibrates at a greater amplitude than that of the normal vibration state. when the suspension is designed to be optimized for the excessive vibration state exhibiting a greater amplitude, the ability to attenuate normal vibrations, having a relatively small amplitude, is deteriorated. In contrast, when the suspension is designed to be optimized for the normal vibration state, vibration attenuation sufficient to attenuate excessive vibrations cannot be expected. Therefore, there is a need to find a method for effectively attenuating vibrations both in the normal vibration state and the excessive vibration state.

Additionally, the suspension may be provided with a friction member which provides frictional force while moving along a support rod during the vibration of the outer tub. In this case, the friction member undergoes material degeneration due to frictional heat generated by the frictional force applied between the friction member and the support rod, which results in considerable reduction of friction and, in the worst case, causes the friction member to stick to the support rod.

SUMMARY

Therefore, embodiments of the present invention are made to solve the problems as described above and it is an object to provide a washing machine in which a friction member generates friction to attenuate vibrations while moving along a support rod in such a manner as to prevent overheating of the friction member.

It is another object to provide a washing machine which is capable of effectively reducing vibrations not only in the normal vibration state, in which the amplitude of an outer tub is within a prescribed range, but also in the excessive vibration state, in which the amplitude of the outer tub deviates from the prescribed range.

It is an object to provide a washing machine which is capable of attenuating vibrations of an outer tub, thereby achieving the improved utility of space inside a casing and, especially, the increased capacity of the outer tub compared with the related art.

It is yet another object to provide a washing machine which is capable of achieving enhanced durability and stability and reducing the generation of noise due to vibrations.

In accordance with one embodiment of the present invention, the above and other objects can be accomplished by the provision of a washing machine including a casing, an outer tub disposed inside the casing to receive wash water therein, a support rod having one end connected to the casing, the other end of the support rod having a support prop, an outer tub supporter to support the outer tub, the outer tub supporter being disposed so as to be movable along the support rod, an elastic member supported by the support prop, the elastic member elastically supporting the outer tub supporter, a first friction unit to apply frictional force between the first friction unit and the support rod, and a second friction unit disposed above the first friction unit so as to be movable along the support rod, the second friction unit applying frictional force between the second friction unit and the support rod, the second friction unit being displaceable relative to the outer tub supporter within a space delimited by the outer tub supporter.

In accordance with another embodiment of the present invention, there is provided a washing machine including a casing, an outer tub disposed inside the casing to receive wash water therein, a support rod having one end connected to the casing, the other end of the support rod having a support prop, an outer tub supporter to support the outer tub, the outer tub supporter being disposed so as to be movable along the support rod, an elastic member supported by the support prop, the elastic member elastically supporting the outer tub supporter, and a first friction unit and a second friction unit movable along the support rod so as to apply frictional force between the first and second friction units and the support rod, wherein the second friction unit is located above the first friction unit, and wherein only the first friction unit is integrally moved with the outer tub supporter while the outer tub vibrates within a prescribed amplitude of vibration, and the first friction unit and the second friction unit are moved together while the outer tub vibrates at a greater amplitude of vibration than the prescribed amplitude of vibration.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:

FIG. 1 is a side sectional view of a washing machine according to one embodiment of the present invention;

FIG. 2 is a partial perspective view illustrating a configuration in which a suspension is mounted to an outer tub illustrated in FIG. 1;

FIG. 3 is a partial enlarged view of portion A illustrated in FIG. 2;

FIG. 4 is a view illustrating a suspension according to one embodiment of the present invention;

FIG. 5 is a view illustrating the operation sequence of the suspension according to one embodiment of the present invention when the vibration displacement of the outer tub increases downward;

FIG. 6 is a view illustrating the operation sequence of the suspension according to another embodiment when the downward displacement of the outer tub gradually increases;

FIG. 7 is a view illustrating the longitudinal cross sections of a first friction unit and a second friction unit located inside an outer tub supporter;

FIG. 8 is a sectional view illustrating a suspension according to another embodiment of the present invention;

FIG. 9 is a view illustrating one embodiment of a second friction member;

FIG. 10 is a front view illustrating a suspension according to a further embodiment of the present invention;

FIG. 11 is a view illustrating the state after the removal of a cover compared with FIG. 10;

FIG. 12( a) is a view illustrating a friction member according to a further embodiment of the present invention, and FIG. 12( b) is a view illustrating a second friction unit including the same; and

FIG. 13 is a view illustrating a second friction member housing formed with a guiding protrusion and a cover formed with a guiding groove to guide movement of the guiding protrusion.

DETAILED DESCRIPTION

Advantages, features, and methods for achieving those of embodiments may become apparent upon referring to embodiments described later in detail together with attached drawings. However, embodiments are not limited to the embodiments disclosed hereinafter, but may be embodied in different modes. The same reference numerals may refer to the same elements throughout the specification.

FIG. 1 is a side sectional view of a washing machine according to one embodiment of the present invention. FIG. 2 is a partial perspective view illustrating a configuration in which a suspension is mounted to an outer tub illustrated in FIG. 1. FIG. 3 is a partial enlarged view of portion A illustrated in FIG. 2. FIG. 4 is a view illustrating a suspension according to one embodiment of the present invention. FIG. 5 is a view illustrating the operation sequence of the suspension according to one embodiment of the present invention when the vibration displacement of the outer tub increases downward. FIG. 6 is a view illustrating the operation sequence of the suspension according to another embodiment when the downward displacement of the outer tub gradually increases.

Referring to FIGS. 1 to 4, the washing machine according to one embodiment of the present invention includes a casing 1 which defines the external appearance of the washing machine, a control panel 11 which includes, for example, operating keys to receive various control instructions input by a user and a display unit to display information regarding the operating state of the washing machine, thereby constituting a user interface, and a door 7 which is rotatably coupled to casing 1 to open or close an introduction/removal hole (not illustrated) for the introduction and removal of laundry.

An outer tub 2, in which wash water is received, is suspended inside casing 1 by a support rod 15, and an inner tub 3, in which laundry is received, is provided inside outer tub 2 so as to be rotatable about a vertical axis. A pulsator 4 is rotatably installed at the bottom of inner tub 3. Inner tub 3 has a plurality of holes for the passage of wash water.

Although the casing defined in the present disclosure is sufficient so long as it forms the external appearance of the washing machine, in particular, the casing may be a stationary body which is immovable so that one end of support rod 15, which suspends outer tub 2 inside the casing, may be fixed by the casing. Casing 1 as described below is merely one example of a structure forming the external appearance of the washing machine and it is specified that the range of the casing described in the claims of the present application should not be limited thereto.

Casing 1 includes a cabinet 12 having an open upper side and a top cover 14 provided at the upper side of cabinet 12, top cover 14 being formed at an approximately central portion thereof with an introduction/removal hole for the introduction and removal of laundry.

Support rod 15 extends by a long length in the longitudinal direction thereof and has one end connected to casing 1 and the other end connected to outer tub 2 via a suspension 100. One end of support rod 15 may be connected to any one of cabinet 12 and top cover 14, and cabinet 12 or top cover 14 may include a connector (not illustrated) which is pivotally connected to support rod 15.

Support rod 15 may include a support prop 140 provided at the other end thereof. Support prop 140 serves to support an elastic member 150 fitted around support rod 15 so as not to be separated from support rod 15. Support prop 140 has a support surface to support a lower end of elastic member 150 so as to prevent elastic member 150 from being separated from support rod 15, and the support surface may have a greater area than the cross section of support rod 15.

Rotation of elastic member 150 about support rod 15 may be restricted by support prop 140. In some embodiments, support prop 140 may be formed with a coupling portion to be coupled to the lower end of elastic member 150, or may be formed with a raised portion to limit the rotation of the lower end of elastic member 150.

A water supply flow path 5 is connected to an external water source such as, for example, a water tap to supply water into outer tub 2 and/or inner tub 3. A water supply valve 6 is provided to control water supply flow path 5. A drive unit 13 serves to drive inner tub 3 and/or pulsator 4. A drain flow path 9 is connected to outer tub 2 to discharge wash water from outer tub 2. A drain valve 8 is provided to control drain flow path 9. A drain pump 10 is installed to drain flow path 9 to pump the discharged wash water to the outside of the washing machine.

Suspension 100 serves to attenuate vibrations of outer tub 2 attributable to the rotation of inner tub 3 or pulsator 4. Suspension 100 includes an outer tub supporter 110, elastic member 150, a first friction unit 120, and a second friction unit 130.

Suspension 100 is coupled to a lower portion of outer tub 2. This coupling may be separable coupling to ensure easy installation and separation of suspension 100. For example, FIG. 3 illustrates a mount 2 a which protrudes from the outer circumferential surface of a lower portion of outer tub 2 for the installation of suspension 100, and mount 2 a is formed with a slit 2 b which extends in the vertical direction and is open in the lateral direction.

To couple suspension 100 and outer tub 2 to each other, once suspension 100 has been installed to support rod 15, support rod 15 is inserted into mount 2 a through a lateral opening of slit 2 b and mount 2 a is seated on outer tub supporter 110 that will be described below. Since the weight of outer tub 2 is continuously applied to outer tub supporter 110, outer tub 2 and outer tub supporter 110 are integrally moved without separation. Meanwhile, separation of suspension 100 for maintenance and repair is easily implemented by pulling suspension 100 slightly downward and removing support rod 15 through the lateral opening of slit 2 b.

Outer tub supporter 110 is configured to support outer tub 2 and is movable along support rod 15. Outer tub supporter 110 may include a tubular slider 111 for the penetration of support rod 15 and a seating portion 112 expanding outward from slider 111 to form a seating surface 112 a on which outer tub 2 is seated. Seating portion 112 may be caught by mount 2 a of outer tub 2 and at least a portion of slider 111 may protrude upward from mount 2 a. A lubricant such as, for example, grease may be applied to a portion of slider 111 coming into contact with support rod 15 (i.e., the inner circumferential surface of an inner elongated bore).

First friction unit 120 and second friction unit 130 are movable along support rod 15 respectively such that frictional force (more particularly, kinetic friction during the vibration of outer tub 2) is generated between the respective friction units and support rod 15. Second friction unit 130 is located above first friction unit 120. Outer tub supporter 110 may include a first receiving region S1 to receive first friction unit 120 and a second receiving region S2 formed above first receiving region S1 to receive second friction unit 130.

First friction unit 120 may be fixed to outer tub supporter 110. In this case, the vertical length of first receiving region S1 is substantially equal to the vertical length of first friction unit 120.

First receiving region S1 and second receiving region S2 may be formed in a receiving body 113 which extends downward from seating portion 112. Receiving body 113 is located inside elastic member 150. Receiving body 113 may include a bottom portion 113 d spaced apart from seating portion 112 and one or more side portions 113 a and 113 b connecting seating portion 112 and bottom portion 113 d to each other. Receiving body 113 may have one or more lateral openings 116 and 117 which are open in the lateral direction to allow first friction unit 120 or second friction unit 130 to be easily inserted into receiving region S1 or S2. In the present embodiment, a pair of first lateral openings 116, which communicate with the interior of first receiving region S1, and a pair of second lateral openings 117, which communicate with the interior of second receiving region S2, are formed between first side portion 113 a and second side portion 113 b. First lateral openings 116 and second lateral openings 117 are separated from each other by a partition 113 c. Lateral openings 116 and 117 function not only to provide easy installation and separation of friction units 120 and 130, but also to dissipate heat generated from friction units 120 and 130. Additionally, a lubricant may be directly injected to friction units 120 and 130 through lateral openings 116 and 117, which provides convenience in maintenance and repair.

Partition 113 c vertically divides a space inside receiving body 113 between the lower surface of seating portion 112 and bottom portion 113 d. On the basis of partition 113 c, first receiving region S1 is a lower region of receiving body 113 and second receiving region S2 is an upper region of receiving body 113. Partition 113 c may connect first side portion 113 a and second side portion 113 b to each other.

With regard to first receiving region S1, the distance between bottom portion 113 d and partition 113 c is substantially equal to the vertical length of first friction unit 120. Thus, first friction unit 120 is fixed to first receiving region S1 and moves integrally with outer tub supporter 110 during the vibration of outer tub 2.

Second receiving region S2 is formed to allow outer tub supporter 110 to be displaceable relative to second friction unit 130. That is, with regard to second receiving region S2, the distance from seating portion 112 to partition 113 c is greater than the vertical length of second friction unit 130, such that outer tub supporter 110 is movable in a section corresponding to the length difference while being separated from second friction unit 130.

Second receiving region S2 may be formed with protrusions 118 a and 118 b at a region thereof which will come into contact with second friction unit 130 when outer tub supporter 110 is moved along with second friction unit 130. More specifically, seating portion 112 may include upper protrusions 118 a which protrude downward from the lower surface of seating portion 112 to the interior of second receiving region S2. Upper protrusions 118 a may be formed around an aperture for the passage of support rod 15. Likewise, partition 113 c may include lower protrusions 118 b which protrude upward to the interior of second receiving region S2. Lower protrusions 118 b may be formed around an aperture for the passage of support rod 15. During the vibration of outer tub 2, second friction unit 130 is moved downward by being pushed by upper protrusions 118 a and moved upward by being pushed by lower protrusions 118 b. This configuration in which second receiving region S2 is provided with protrusions 118 a and 118 b may reduce the collision area between outer tub supporter 110 and second friction unit 130, thereby reducing collision noise.

Meanwhile, friction between two friction units 120 and 130 and support rod 15 exhibits different aspects based on the amplitude of vibration of outer tub 2. For example, when operating the washing machine, in the case where outer tub 2 resonates based on the physical properties of the entire vibration system, or for an excessive vibration period, during which excessive vibrations are generated due to the unbalanced arrangement of clothing inside inner tub 3, first friction unit 120 and second friction unit 130 are moved integrally with outer tub supporter 110, causing kinetic friction between friction units 120 and 130 and support rod 15. Accordingly, for the excessive vibration period, vibration energy is more positively dissipated by friction of both first and second friction units 120 and 130.

On the other hand, for a period, during which the amplitude of vibration of outer tub 2 is sufficiently lower than that of the excessive vibration period (e.g., a normal vibration period), second friction unit 130 remains at a given position on support rod 15 while being separated from outer tub supporter 110, and outer tub supporter 110 is displaced relative to second friction unit 130. Accordingly, second friction unit 130 does not function to attenuate vibrations, whereas first friction unit 120 is continuously moved integrally with outer tub supporter 110 so as to dissipate vibration energy. Outer tub 2 can vibrate relatively freely because vibration attenuation by friction is implemented only by first friction unit 120.

Suspension 100 implements vibration attenuation using one friction unit 120 during the relatively stable period (e.g., a normal vibration period), but implements positive attenuation by friction using two friction units 120 and 130 during the excessive vibration period while the washing machine is operating. That is, the washing machine according to the present embodiment allows outer tub 2 to be moved relatively freely within a predetermined allowable amplitude range in consideration of, for example, the durability of the appliance and an allowable vibration displacement, but more positively attenuates vibrations to limit the amplitude of vibration when vibrations are generated beyond a given level. As such, the washing machine shows different aspects of vibration attenuation based on the amplitude of vibration.

Meanwhile, although two friction units are provided as described above, as a comparative embodiment to the present embodiment, a suspension in which second friction unit 130 is located below first friction unit 120 will be described below. The following description is referenced with FIG. 6.

FIG. 6 illustrates the sequence of downward movement of an outer tub supporter 110′ in the case of excessive vibration. More specifically, in FIG. 6( a) illustrating the case where outer tub 2 has been raised to an uppermost position during vibration, outer tub 2 begins to be displaced downward. As exemplarily illustrated in FIG. 6( a), first friction unit 120 begins to be moved integrally with outer tub supporter 110′, whereas a lower end of second friction unit 130 is separated from outer tub supporter 110′. Second friction unit 130 remains at a fixed position on support rod 15 until outer tub supporter 110′ is moved downward and begins to push an upper end of second friction unit 130 (see FIG. 6( b)). That is, outer tub supporter 110′ has been displaced independently of second friction unit 130 starting from the state of FIG. 6( a) to reach the state of FIG. 6( b).

In the state of FIG. 6( b), outer tub supporter 110′ comes into contact with second friction unit 130, and first friction unit 120 and second friction unit 130 begin to be moved together. Thereafter, in FIG. 6( c) illustrating the case where outer tub 2 has been located at a lowermost position, second friction unit 130 remains in contact with outer tub supporter 110′. Although not illustrated, after state of FIG. 6( c), outer tub supporter 110′ is again moved upward by the restoration force of elastic member 150, thereby returning to the state of FIG. 6( a).

In FIGS. 6( a) to 6(c), during the downward movement of outer tub 2, the area where friction by second friction unit 130 is applied is designated by mf′ and the area where friction by first friction unit 120 is applied is designated by ff′. As is exemplarily illustrated in FIGS. 6( a) to 6(c), an area cf′ is formed where the area mf′ and the area ff′ overlap each other. In particular, the area cf′ is a section where first friction unit 120 applies friction immediately after second friction unit 130 applies friction. Thus, frictional heat is concentrated in the area cf′. Accordingly, a portion of first friction unit 120 coming into contact with support rod 15 may be degenerated by heat and, depending on the material, may stick to support road 15. In particular, since the downward movement of outer tub 2 accelerates more than the upward movement of outer tub 2 due to gravity, friction between friction units 120 and 130 and support rod 15 and heat emission increase during the downward movement of outer tub 2. Additionally, in the area cf′, as outer tub 2 begins to be moved upward from the lowermost position (FIG. 6( c)) again, friction by first friction unit 120 is again applied for a given time, which aggravates heat emission due to friction.

To solve the above-described problem, embodiments of the present invention proposes to dispose second friction unit 130 below first friction unit 120. How this structure effectively solves overheating due to friction compared with a comparative embodiment will be described in detail with reference to FIG. 5. First, reference characters designated in FIG. 5 are as follows.

-   -   (a): the case where outer tub 2 is located at the uppermost         position during vibration     -   (b): the state in which outer tub supporter 110 is moved         downward and begins to push the upper end of second friction         unit 130     -   (c): the case where outer tub 2 is located at the lowermost         position     -   ΔH1: an area where outer tub supporter 110 is displaced         independently of second friction unit 130 during the downward         movement of outer tub 2     -   ΔH2: a displacement of second friction unit 130     -   mf: an area where friction is applied by second friction unit         130     -   ff: an area where friction is applied by first friction unit 120     -   cf: an area where the area mf and the area ff overlap each other

As opposed to the previously described embodiment, friction is not applied by second friction unit 130 immediately after friction is applied by first friction unit 120 in the overlapping area cf. After outer tub supporter 110 is moved independently of second friction unit 130 at least in the area ΔH1, friction is applied by second friction unit 130. Accordingly, no increase in frictional heat occurs in the area cf while outer tub supporter 110 is displaced by at least ΔH1.

In some embodiments, assuming that the vertical length of second receiving region S2 is increased to increase the independent movement length of outer tub supporter 110 relative to second friction unit 130, the time taken until second friction unit 130 enters the overlapping area cf after first friction unit 120 passes through the overlapping area cf may be increased. In this sense, by appropriately designing the maximum displaceable length of outer tub supporter 110 relative to second friction unit 130, the overlapping area cf may not be generated even in the case where the amplitude of vibration is the same as the comparative embodiment.

Meanwhile, when outer tub 2 is again moved upward from the lowermost position, no friction is applied by second friction unit 130 for a given time until first friction unit 120 again reaches the overlapping area cf and, correspondingly, the temperature increase in the overlapping area cf may be restricted.

Meanwhile, although first friction unit 120 may be moved integrally with outer tub supporter 110, in some embodiments, outer tub supporter 110 may also be moved with a slight displacement relative to first friction unit 120. However, even in this case, the maximum displacement at which first friction unit 120 is movable independently of outer tub supporter 110 is smaller than the allowable maximum displacement for second friction unit 130.

Each of first friction unit 120 and second friction unit 130 may include at least one friction member to come into contact with the outer circumferential surface of support rod 15. Hereinafter, the friction member of each friction unit is referred to as a first friction member 121 or a second friction member 131. These friction members 121 and 131 may be formed of a porous fiber material such as, for example, felt, or may be formed of an elastic material such as, for example, rubber. In addition, in terms of the shape, friction members 121 and 131 may have a tubular shape so as to be fitted around support rod 15, or may take the form of a flexible sheet or band so as to be wound around the outer circumferential surface of support rod 15. In particular, the fibrous friction member has excellent absorbency for a lubricant.

Elastic member 150 is supported by support prop 140 and elastically supports outer tub supporter 110. In the present embodiment, elastic member 150 is a compression spring which elastically supports seating portion 112. As such, elastic member 150 is compressed when outer tub 2 is displaced downward and elastically rebounds after being compressed beyond a given level so as to push outer tub supporter 110 upward.

FIG. 7 is a view illustrating the longitudinal cross sections of first friction unit 120 and second friction unit 130 located inside outer tub supporter 110. Referring to FIG. 7, first friction unit 120 may include a tubular first friction member housing 122 and first friction member 121 placed inside first friction member housing 122 to generate friction between first friction unit 120 and support rod 15.

Similar to first friction unit 120, second friction unit 130 may include a second friction member housing 132 and second friction member 131 placed inside second friction member housing 132. Additionally, second friction unit 130 may further include a shock absorbing member 133 located above and/or below second friction member housing 132.

Shock absorbing member 133 may be formed of a porous fiber material such as, for example, felt and serve to alleviate shocks between second friction unit 130 and second receiving region S2 and to reduce collision noise therebetween.

FIG. 8 is a sectional view illustrating a suspension according to another embodiment of the present invention. Suspension 200 according to the present embodiment is identical to that of the previously described embodiment in that an outer tub supporter 210 includes slider 111, seating portion 112, and receiving body 113, but has a difference in that it further includes outwardly protruding portions 219 a and 219 b which more protrude outward from the periphery of receiving body 113 than side portions 113 a and 113 b.

In this embodiment, outer tub supporter 210 includes the first outwardly protruding portion 219 a and the second outwardly protruding portion 219 b which extend downward from seating portion 112 with lateral openings 217 interposed therebetween, but is not limited thereto. A single outwardly protruding portion may be formed around the periphery of receiving body 113. In this case, the outwardly protruding portion may be formed with an opening in a region S thereof overlapping lateral opening 217 of receiving body 113.

Outwardly protruding portions 219 a and 219 b extend downward from seating portion 112 and are supported at lower ends thereof by elastic member 150. First receiving region S1 and second receiving region S2 are formed in receiving body 113. In particular, at least a part S of second receiving region S2 extends to the interior of the outwardly protruding portions 219 a and 219 b. Outwardly protruding portions 219 a and 219 b serve to enhance the rigidity of outer tub supporter 210 and, in particular, reinforce the interface between seating portion 112 and receiving body 113.

FIG. 9 is a view illustrating one embodiment of a second friction member. Hereinafter, a friction member 231, which will be described below with reference to FIG. 9, has substantially the same configuration as suspension 100 according to the above-described embodiment of the present invention, but is assumed to be applied to a suspension (not illustrated) that is not provided with protrusions 118 a and 118 b.

Referring to FIG. 9, second friction member 231 may take the form of a sheet and may be wound around the outer circumference of support rod 15 inside second friction member housing 132. Second friction member 231 may be formed of a flexible fiber material or rubber.

A portion of second friction member 231 which will collide with second receiving region S2 when second friction member 131 is moved along support rod 15 may be more raised than a peripheral portion. The raised portion of second friction member 231 protrudes outward from second friction member housing 132. As second friction member 231 is moved along support rod 15, the raised portion comes into contact with second receiving region S2. When second friction member 231 collides with second receiving region S2, the raised portion serves to alleviate shocks and to reduce the contact area therebetween, resulting in reduced shock noise.

More specifically, as illustrated in FIG. 9, convex portions 231 a and concave portions 231 b may be alternately formed at an upper end and a lower end of second friction member 231. In this case, convex portions 231 a formed at the upper end of second friction member 231 come into contact with the lower surface of seating portion 112, and convex portions 231 a formed at the lower end of second friction member 231 come into contact with the upper surface of bottom portion 113 d of receiving body 113. As such, even in the case where no protrusions 118 a and 118 b are formed at second receiving region S2, the contact area between second friction member 231 and outer tub supporter 110 may be reduced and, in particular, shock noise may be reduced thanks to shock absorption by convex portions 231 a.

FIG. 10 is a front view illustrating a suspension 300 according to a further embodiment of the present invention. FIG. 11 is a view illustrating the state after the removal of a cover 350 compared to FIG. 10. FIG. 12( a) is a view illustrating a friction member 331 according to a further embodiment of the present invention, and FIG. 12( b) is a view illustrating a second friction unit 330 including the same. FIG. 13 illustrates a second friction member housing 332 formed with a guiding protrusion 332 c and cover 350 formed with a guiding groove 351 to guide movement of guiding protrusion 332 c. In particular, FIG. 13 is a cutaway view of cover 350 to show guiding groove 351.

Referring to FIGS. 10 to 13, suspension 300 according to the present embodiment includes an outer tub supporter 210′, and cover 350 coupled to outer tub supporter 210′ and supported by elastic member 150. Outer tub supporter 210′ is similar to outer tub supporter 210 of the previously described embodiment, but has a difference in that it has no protrusions 218 a and 218 b. Thus, a detailed configuration of outer tub supporter 210′ follows the above description, and a detailed description thereof will be omitted below.

Cover 350 is configured as a component separate from outer tub supporter 210′ and is coupled to outwardly protruding portions 219 a and 219 b. Cover 350 may include a cover lower end portion 353 supported by elastic member 150 and an insertion portion 352 protruding upward from cover lower end portion 353 so as to be inserted between the first outwardly protruding portion 219 a and the second outwardly protruding portion 219 b. As insertion portion 352 is inserted into an opening between the first outwardly protruding portion 219 a and the second outwardly protruding portion 219 b, cover 350 is constrained so as not to rotate about support rod 15.

Cover 350 may be separably coupled to outer tub supporter 210′. This coupling is not necessarily limited to fixed coupling, which maintains cover 350 and outer tub supporter 210′ in an integrated state after external force is removed. That is, even in the case where cover 350 is freely separable from outer tub supporter 210′, cover 350 may be moved integrally with outer tub supporter 210′ due to the elastic support force of elastic member 150. Even in this case, both cover 350 and outer tub supporter 210′ are defined as maintaining the coupled state thereof.

Lower end portion 353 of cover 350 supported by elastic member 150 has a ring shape and extends to the bottom of the opening formed between the outwardly protruding portions 219 a and 219 b. Thus, the entire lower end portion 353 may be evenly supported by elastic member 150.

One of the inner circumferential surfaces of cover 350 and second friction unit 330 may be formed with a vertically extending guide groove 351 and the other one may be formed with a guiding protrusion 332 c to be guided along guiding groove 351. In the embodiment, vertical guiding protrusion 332 c is formed at the outer circumference of the second friction member housing 332 and guiding groove 351 is formed in the inner circumferential surface of cover 350 such that guiding protrusion 332 c is inserted into and guided by guiding groove 351. Guiding protrusion 332 c and guiding groove 351 may specify an accurate assembly position of second friction unit 330 and allow second friction unit 330 to be stably moved along support rod 15 without shaking.

Second friction unit 330 may include a second friction member 331 formed with convex portions 331 a at an upper end and/or a lower end thereof, and a second friction member housing 332 in which two or more second friction members 331 are received at upper and lower positions.

Second friction member 331 may take the form of a sheet and may be alternately formed with convex portions 331 a and concave portions 331 b. Second friction member 331 may be wound around the outer circumference of support rod inside second friction member housing 332. Second friction member 331 may be formed of a flexible fiber material or rubber.

Second friction member housing 332 internally forms a space in which two or more second friction members 331 may be received. Second friction members 331 are received in an upper region 332 a and a lower region 332 b of the space. At this time, convex portions 331 a of each second friction member 331 may protrude upward or downward from the second friction member housing 332 so as to come into contact with the second receiving region S2 when second friction unit 330 is moved along support rod 15. Second friction member housing 332 may include a dividing member such as, for example, a rib or a partition which divides the space into the upper region and the lower region.

Although second friction member 331 is similar to second friction member 231 as described above in that it has convex portions 331 a and concave portions 331 b, in consideration of a structure in which the two second friction members 331 are received at upper and lower positions inside the second friction member housing 332, it is sufficient to provide convex portions and concave portions at only one of the upper and lower ends of each second friction members 331 (see FIG. 12( a)).

As is apparent from the above description, the washing machine of the present disclosure has the effect of preventing the area where the movement ranges of a first friction unit and a second friction unit, which are arranged at upper and lower positions along a support rod, from being overheated by frictional heat. Accordingly, embodiments of the present invention have the effect of preventing the material of the portions of the first friction unit and the second friction unit that come into contact with the support rod from being degenerated by heat.

In addition, since the attenuation of friction by the first friction unit and the second friction unit may be stably realized and the portions of the first and second friction units that come into contact with the support rod may be maintained rigid without deformation, embodiments of the present invention have the effect of enabling the first and second friction units to be moved along the support rod without shaking.

In addition, embodiments of the present invention have the effect of effectively attenuating vibrations not only in the normal vibration state in which the amplitude of vibration of an outer tub is within a prescribed range, but also in the excessive vibration state in which the amplitude of vibration of the outer tub deviates from the prescribed range.

In addition, embodiments of the present invention have the effect of attenuating vibrations of the outer tub, thereby achieving the improved utility of space inside a casing and, especially, increasing the capacity of the outer tub.

In addition, embodiments of the present invention have the effect of achieving enhanced durability and stability of the washing machine and reducing the generation of noise due to vibrations.

Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternatives uses will also be apparent to those skilled in the art. 

What is claimed is:
 1. A washing machine comprising: a casing; an outer tub disposed inside the casing, to receive wash water therein; a support rod having one end connected to the casing, the other end of the support rod having a support prop; an outer tub supporter to support the outer tub, the outer tub supporter being disposed so as to be movable along the support rod; an elastic member supported by the support prop, the elastic member elastically supporting the outer tub supporter; a first friction unit to apply frictional force between the first friction unit and the support rod; and a second friction unit disposed above the first friction unit and movable along the support rod, the second friction unit applying frictional force between the second friction unit and the support rod, wherein the second friction unit is displaceable relative to the outer tub supporter within a space delimited by the outer tub supporter.
 2. The washing machine of claim 1, wherein the outer tub supporter includes: a seating portion forming a seating surface to allow the outer tub to be seated thereon; and a receiving body including a second receiving region extending downward from the seating portion so as to receive the second friction unit therein and a first receiving region formed below the second receiving region so as to receive the first friction unit therein.
 3. The washing machine of claim 2, wherein the receiving body includes an opening configured to be open in a lateral direction so as to outwardly expose the interior of at least one of the first receiving region and the second receiving region.
 4. The washing machine of claim 2, wherein the elastic member elastically supports the seating portion.
 5. The washing machine of claim 2, wherein the receiving body includes a partition to separate the first receiving region and the second receiving region.
 6. The washing machine of claim 5, wherein the second friction unit is moved downward by the seating portion and moved upward by the partition.
 7. The washing machine of claim 6, wherein at least one of the seating portion and the partition includes a protrusion formed at a portion thereof coming into contact with the second friction unit.
 8. The washing machine of claim 2, wherein the outer tub supporter further includes an outwardly protruding portion extending downward from the seating portion and protruding outward beyond the receiving body.
 9. The washing machine of claim 8, wherein the outwardly protruding portion is supported by the elastic member.
 10. The washing machine of claim 8, further comprising: a cover coupled to the outer tub supporter, a lower end portion of the cover protruding outward from the outer tub supporter being supported by the elastic member.
 11. The washing machine of claim 10, wherein any one of the cover and the second friction unit is formed with a vertically extending guiding groove and the other one is formed with a guiding protrusion to be guided along the guiding groove.
 12. The washing machine of claim 11, wherein the second friction unit includes: a tubular friction member housing to be fitted around the support rod; and a friction member disposed inside the tubular friction member housing so as to generate friction with the support rod, and wherein the guiding groove or the guide protrusion is formed at the tubular friction member housing.
 13. The washing machine of claim 1, wherein the second friction unit includes a friction member formed of a flexible material to apply friction between the second friction unit and an outer circumferential surface of the support rod.
 14. The washing machine of claim 13, wherein the friction member includes a collision portion on one or both of an upper end of the friction member or a lower end of the friction member which collides with the second receiving region when the friction member is moved along the support rod, and the collision portion has a convex shape more raised than a peripheral portion.
 15. The washing machine of claim 14, wherein the friction member includes convex portions corresponding to the convex shape and concave portions near the convex portions, the convex portions and the concave portions being alternately formed.
 16. The washing machine of claim 15, wherein the friction member takes the form of a sheet wound around the support rod.
 17. The washing machine of claim 1, wherein the first friction unit is disposed so as to be fixed to the outer tub supporter.
 18. A washing machine comprising: a casing; an outer tub disposed inside the casing, receive wash water therein; a support rod having one end connected to the casing, the other end of the support rod having a support prop; an outer tub supporter to support the outer tub, the outer tub supporter being disposed so as to be movable along the support rod; an elastic member supported by the support prop, the elastic member elastically supporting the outer tub supporter; and a first friction unit and a second friction unit movable along the support rod so as to apply frictional force between the first and second friction units and the support rod, wherein the second friction unit is located above the first friction unit, and wherein only the first friction unit is integrally moved with the outer tub supporter while the outer tub vibrates within a prescribed amplitude of vibration, and the first friction unit and the second friction unit are moved together while the outer tub vibrates at a greater amplitude of vibration than the prescribed amplitude of vibration. 